MacConkey HiVeg™ Broth w/ Neutral Red

MacConkey HiVeg Media are differential media recommended for the selection and recovery of Enterobacteriaceae and related enteric gram-negative bacilli. The following media are available.

(MV008) MacConkey HiVeg™ Agar without CV, with 0.003% NR and 1.5% Agar
(MV008A) MacConkey HiVeg™ Agar without CV, with 0.0075% NR and 1.2% Agar
(MV008B) MacConkey HiVeg™ Agar without CV with 0.003% NR and 1.2% Agar
(MV081) MacConkey HiVeg™ Agar with CV, NaCl, 0.003% NR and 1.5% Agar
(MV081A) MacConkey HiVeg™ Agar with CV, NaCl, 0.005% NR and 1.5% Agar
(MV081B) MacConkey HiVeg™ Agar with CV, NaCl, 0.003% NR and 1.35% Agar
(MV082) MacConkey HiVeg™ Agar without CV and NaCl, with 0.004% NR and 2.0% Agar
(MV082A) MacConkey HiVeg™ Agar without CV and NaCl, with 0.0075% NR and 1.2% Agar
(MV051) MacConkey HiVeg™ Agar, Modified
(MV061) MacConkey HiVeg™ Agar with Bromo Thymol Blue
(MV298) MacConkey Sorbitol HiVeg™ Agar
(MV007) MacConkey HiVeg™ Broth with Neutral Red
(MV083) MacConkey HiVeg™ Broth Purple with BCP

Intended Use

MV008, MV008B and MV008A: These are modifications of MacConkey Agar prepared without crystal violet. These are slightly less selective than the formula of MacConkey HiVeg Agar (MV081).

MV081, MV081A and MV081B: These agar media contain crystal violet and are very selective compared to MV008. They suppress a number of gram-positive bacteria including Staphylococci.

MV082: MacConkey HiVeg Agar is the modification of MacConkey Agar prepared as per Medical Microbiology by Cruickshank et al (2). It is a differential medium which restricts the swarming of most Proteus species thereby permitting greater ease in the detection and isolation of enteric organisms. It is specially useful for culturing urine specimens which may contain large number of Proteus species as well as potentially pathogenic gram-positive organisms. Enterococci produce compact tiny reddish colonies either on or beneath the surface.

MV082A: It is a modification of MV082 containing Synthetic detergent and reduced amount of agar.

MV051: This agar medium is used in membrane filtration procedure for the detection and isolation of Klebsiella species from water and other sources.

MV061: This medium has almost the same composition as MV008 except that the indicator is bromothymol blue instead of neutral red.

MV298: It contains sorbitol instead of lactose and is recommended for detection of enteropathogenic Escherichia coli strains (3).

MV007: This medium is a modification of MacConkey Broth with Neutral Red (M007) which is considered as a standard medium for the primary isolation as well as presumptive identification of coliform-aerogenes group of organisms in food and water. The medium contains neutral red as an indicator.

MV083: This broth has similar use as MV007 except that it contain bromo cresol purple as an indicator instead of neutral red (4, 5). This liquid medium is meant for presumptive identification of coliforms from a variety of specimens such as water, milk and food.

Formulae of different MacConkey Media

Ingredients (Grams/Litre)	MV008	MV008A	MV008B	MV081	MV081A	MV081B	MV082	MV082A	MV298	MV051	MV061	MV007	MV083
HiVeg peptone	17	23	17	1.5	20	1.5	23	23	17	17	17	23	23
HiVeg peptone No. 3	3		3						3	3	3
HiVeg hydrolysate	-			1.5		1.5
HiVeg peptone No. 2					17		17
Lactose	10	10	10	10	10	10	10	10		10	10	10
Sorbitol									10
Inositol										10
Synthetic detergent	1.5	2	1.5	1.5	1.5	1.5		2	1.5	1.5	1.5	2
Synthetic detergent No. V							2						2
Sodium chloride	5	5	5	5	5	5			5	5	5	5	5
Crystal violet				0.001	0.001	0.001			0.001	0.001
Neutral red	0.03	0.075	0.03	0.03	0.05	0.03	0.04	0.075	0.03	0.03		0.075
Bromo cresol purple													0.01
Bromo thymol blue											0.03
Agar	15	12	12	15	15	13.5	20	12	13.5	13.5	15
pH (at 25°C) ± 0.2	7.1	7.4	7.1	7.1	7.2	7.1	7.4	7.4	7.1	7.1	7.1	7.4	7.4
Grams per litre	51.53	52.07	48.53	51.53	51.55	50.03	55.04	47.07	50.03	50.03	51.53	40.07	40.01

Directions

A) For MacConkey HiVeg Agars: Suspend the appropriate quantity of medium as specified on the label, in 1000 ml distilled water. Heat to boiling with gentle swirling to dissolve the agar completely. Sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes. Avoid overheating. Cool to 45 - 50°C and pour into sterile petriplates. The surface of the medium should be dry when inoculated. For MacConkey HiVeg Agar, Modified (MV051), autoclaving is not recommended. After boiling, cool the medium to 50°C, and add 50 mg Carbenicillin per litre and mix well before pouring in sterile petri plates.

B) For MacConkey HiVeg Broths: Suspend the appropriate amount of medium as specified on the label, in 1000 ml distilled water. Heat to dissolve the medium completely. Distribute into tubes with inverted Durham's tubes and sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes. Cool the tubes before inoculation. Incubate the inoculated media aerobically at 35 - 37°C. After 18 - 24 hours, examine agar plates and the broth tubes for growth, acid and gas production.

Principle and Interpretation

These media are prepared by using vegetable peptone in place of animal based peptones which makes the medium free of BSE/TSE risks. MacConkey HiVeg Agar is the modification of MacConkey Agar which is the earliest selective and differential medium for cultivation of enteric microorganisms from a variety of clinical specimens (7, 8). Subsequently MacConkey HiVeg Agar and Broth like the conventional medium have been recommended for use in microbiological examination of foodstuffs (9) and for direct plating / inoculation of water samples for coliform counts (10, 14). Medium contains protein, synthetic detergents, sodium chloride and two dyes. The selective action of this medium is attributed to crystal violet and synthetic detergents, which are inhibitory to most species of gram-positive bacteria. Gram-negative bacteria usually grow well on the medium and are differentiated by their ability to ferment lactose. Lactose fermenting strains grow as red or pink coloured colonies. The red colour is due to production of acid from lactose, absorption of neutral red and a subsequent colour change of the dye when the pH of medium falls below 6.8. Lactose non-fermenting strains, such as Shigella and Salmonella are colourless and transparent and typically do not alter appearance of the medium. Yersinia enterocolitica may appear as small, non-lactose fermenting colonies after incubation at room temperature. Sorbitol MacConkey HiVeg Agar is the modification of conventional Sorbitol MacConkey Agar which is based on the formulation described by Rappaport and Henig (3). In this medium lactose has been replaced by sorbitol as it is a recommended medium for isolation of enteropathogenic Escherichia coli O157:H7. Escherichia coli O157:H7 does not ferment sorbitol and hence produces colourless colonies. This organism has been recognized as a cause of haemorrhagic colitis (12). Sorbitol MacConkey HiVeg Agar however should not be used solely to detect pathogenic Escherichia coli O157:H7 strains as some non-toxic strains will also not ferment sorbitol. It is necessary to select suspected colonies for further identification. MacConkey HiVeg Agar, Modified (MV051) is the modification of medium which is prepared according to the formulation recommended in Standard Methods (10). Klebsiella species are associated with coliforms in water supply distribution systems and are often present as a major component in industrial wastes of paper mill, textile and other industries. The normal coliform population in human and other warm blooded animal faeces may contain 30 to 40% Klebsiella strains. Out of this population 4% are of bacterial pneumonia cases and 18% of urinary tract. Infections are caused by pathogenic strains of Klebsiella. In this medium inositol is incorporated in place of lactose while added Carbenicillin makes the medium selective for Klebsiella species. Further, this method reduces the necessity for biochemical testing of pure strains, however, preliminary verification of differentiated colonies is recommended.